Clear glass. 



Experiment 65 



=14 



In the absence of any back- 

 ground of sufficient reflecting 

 power, the pup© apparently 

 tend towards the commoner 

 darker varieties. 



Experiment 2 



7 to 13 



20 to 25 

 „ 43 



56 to 61 

 » 67 



70 to 74 



91 & 92 



93 



94 to 97 



Totals. 



Results expressed as ] 

 percentages of total J 



Experiment 55 was omitted 

 (see description). 



Very powerful effect in pro- 

 ducing bright pupae, 71 % being 

 the lightest forms. These are 

 the most extreme results ob- 

 tained in this direction, and 

 contrast very strongly with the 

 effect of silver, probably corre- 

 sponding to the differences in 

 absorption and reflection of light 

 which make the "gilt" yellow 

 and the silver grey. 



It was clearly shown in the 

 account of Experiment 67, 

 that the "gilt" surface is per- 

 fectly effective when separated 

 from the larvffi by a layer of 

 glass. 



Silver and tin surfaces. 



Experiment 14 



26 to 30 

 62 & 63 

 90 



Totals.. 



Results expressed as | 

 percentages of total j 



i ^ 

 15 9 



1 



16 



17 



30-8 32-7 



1 1 



2 1 

 2 5 



2 ' 



13-5 



13-5 



9-6 



= 5 



:12 



=32 



-. 3 



52 



This surface, bright as it is, 

 tends somewhat strongly to pro- 

 duce dark pupre rather than 

 light. The difference between 

 the effects of "gilt" and silver 

 is far more pronounced than in 

 V. urticce. 



Deep red paper. 



Experiment 77 



Red glass. 



Experiment 36 

 45 



Red gelatine. 

 Experiment 35 



=3 



Beginning at the least refran- 

 gible end of the spectrum, we 

 find that a deep red background 

 in strong light produces the 

 darkest jDupte. On the other 

 hand, red glass and red gelatine, 

 placed in front of white paper 

 and light wood backgrounds 

 respectively, produce light pup;e. 

 The red gelatine especially gave 

 a very pure light, almost exactly 

 corresponding to the rays chiefly 

 reflected from the red back- 

 ground. The remarkable diffe- 

 rence in the effects of the same 

 light will be considered at the 

 end of this comparison. 



Deep orange paper. 



Experiment 33 

 78 



Passing from a red back- 

 ground to an orange one, which 

 reflects the same rays, with the 

 addition of a narrow strip of 

 orange and yellow, we find an 

 entirely opposite result, the pupa 

 being bright green. 



